He purchased the butterfly as seen in the photos, I'm not sure what the wings are made of but it looks like some fairly thin cloth/nylon/spandex type material. In the Instructable he says that the wings will be finished in fabric that matches the dress.
Some of this technology has been perfected and mass marketed in the RC helicopter and airplane world. Minature recievers, lithum ion batteries, tiny servos made from motors and a leadscrew occuping less than 1/2 of a CC. The green led in this case tells the operator that the system is powered and ready. I would have modified a Ready to fly Blade MCX which costs $135 and includes a co-axial 4 channel helicopter, 4 channel radio, battery and charger...
A moving mechanical butterfly in your hair would really turn some heads. It seems that DelFly is on to something similar although they could use some tips in making their ornithopters more "butterfly" looking. And, of course, remove the camera as well. Getting it to alight on top of the brides hair whilst in the course of reciting her vows would also get a few "wows".
This is a neat project indeed. My guess is a small gearmotor, although I can think of a couple of ways to do it using a small motor similar to the vibration motor in a pager. Then a PWM drive to slow it down, and it is done, except if it needs to be checking for movement to tigger the motion.
But this project could indeed be the start of another fad.
Festo's BionicKangaroo combines pneumatic and electrical drive technology, plus very precise controls and condition monitoring. Like a real kangaroo, the BionicKangaroo robot harvests the kinetic energy of each takeoff and immediately uses it to power the next jump.
Design News and Digi-Key presents: Creating & Testing Your First RTOS Application Using MQX, a crash course that will look at defining a project, selecting a target processor, blocking code, defining tasks, completing code, and debugging.
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